Next week the final few hundred of Britain’s Korean War veterans will assemble outside the Ministry of Defence (MoD) building on Victoria Embankment. Most of the 81,000 British service personnel deployed to Korea between 1950 and 1953 have now long surpassed their 80th year. As a result, their numbers have dwindled.

Some will require a sturdy stick to stand on parade, for others, regimental berets will cover grey heads. But they will line up as proud as the first time they ever pulled on their uniforms. For the men who fought in what has become known as Britain’s “forgotten war” have won their final battle.

After years of campaigning, their sacrifice is to be officially remembered: a permanent memorial cast in bronze and portland stone, honouring those who fought in Korea and the 1,106 who never returned.

The unveiling ceremony of London’s first public memorial to the Korean War will be attended by 300 members of the British Korean’s Veterans Association (BKVA) and led by the Duke of Gloucester who will be delivering a personal message from the Queen. The first Victoria Cross she ever invested was to Korea hero Bill Speakman, after ascending the throne in 1952.

Yet Bill, who in 1951 led a grenade charge on enemy troops and when he ran out of ammunition launched beer bottles instead, was one of the lucky ones to be honoured when he returned home. Most of the soldiers arrived back to deserted train stations and cab ranks. Unlike World War Two, there was to be neither V-Day parades, nor bunting hung in the streets for those that served in Korea.

When, in 1950, the Communist-backed forces of the North invaded the South, Britain became the second largest contributor out of 21 countries that joined the UN forces in its first ever armed response. Yet at the time, nobody living in the rubble of post-war Britain seemed to have any appetite for another conflict.

The lack of recognition is something veterans have struggled against ever since, even following the formation of the BKVA in 1981. Six years after that, the Queen installed a memorial plaque to the heroes of Korea in the crypt of St Paul’s Cathedral. But their dream was always to secure what is being unveiled on Wednesday.

London has, until now, been the only capital city of the coalition of countries that fought under the UN flag not to have an accessible memorial. Alan Guy, 82, who has been instrumental in the campaign, says he and his fellow veterans “never thought it would get off the ground in our lifetimes”.

“There were more deaths in Korea than in Afghanistan, Iraq and the Falklands put together,” he says. “Now at least we will never be forgotten.”

Key to making it happen has been the Korean government itself, even meeting the overall £1 million cost of the six metre tall memorial, which is a bronze statue of a British soldier created by sculptor Philip Jackson, standing in front of a portland stone obelisk on a base of Welsh slate. Last autumn, president Park Geun-hye made a state visit and was accompanied by the Duke of Cambridge at the ground-breaking ceremony. On Wednesday, a delegation of 150 Koreans, including the minister of foreign affairs, will attend the unveiling.

Mr Guy, who served with the Royal Army Medical Corps in Korea between February 1952 and September 1953, met Prince William at last year’s ceremony, and says he expressed concern to him about the number of Korean veterans suffering from Post Traumatic Stress Disorder. Certainly many still struggle with what they experienced.

Photographs from the frontline show a shelled-out wasteland equal in desolation to the Western Front. Even before the conflict, Korea, previously part of the Japanese Empire which had been divided by the 38th parallel between the communist North and Western-backed South in 1945, was desperately poor. After three years of fierce fighting between Mao Tse-tsung’s Chinese and the North against the UN forces, it had been blown to pieces.

Michael Griffin, an 82-year-old who served in Korea with the Royal Norfolk Regiment, was one of many teenagers who signed up through national service. “We were very green and had never seen any action before,” he says. Griffin recalls conditions akin to World War One with soldiers existing in filthy trenches. In winter, temperatures plunged below minus 40 degrees. In summer, rats and malarial mosquitoes swarmed.

“There were lots of booby traps, bundles of spiked masher grenades with trip wires. There were dead Chinese soldiers hung on the barbed wire and nobody could do anything about it because there were too many mines around. There were at least between 200 and 300 bodies, they called it Stink Alley.”

Despite the ordure of what he faced, Griffin remembers well his return home to a nonplussed Britain in October 1952. “We docked at Southampton and got the train to Norwich. I had to walk up to Norwich Castle, where the regiment was based. We thought they might have put up a couple of flags, or something, but they didn’t even have any beds for us.”

Griffin is a member of the Surrey West Branch of the BKVA, as is 81-year-old Arthur Moulder.

Former Royal Fusilier Arthur Moulder

The former Royal Fusilier says there is one death in particular which he still remembers. The attack came during a 10-man patrol in the witching hours of Remembrance Day, 1952, when, after hours of creeping through the pitch black, they encountered a group of Chinese soldiers.

“We grabbed one of them but he managed to get his hands free and let off a grenade. It killed him and a lot of others were wounded quite badly. There was panic everywhere.”

In the chaos, Moulder – who had been hit by some shrapnel in his arm which is still there today - was searching frantically for his friend Corporal “Taffy” Williams. “We couldn’t find him anywhere, it was so dark and he wasn’t making any noise. I realised it was because he was dead.”

That attack took place on Hill 355, known to British troops as “Little Gibraltar” due to its steep rocky ridges, and fiercely contested as a key strategic position. Yet it was on another piece of bureaucratically-titled high ground a few miles away, where the bloodiest battle of the war took place.

Hill 235, a vantage point over the Imjin River, was where, in 1951, 750 men of the 1st Bn The Gloucestershire Regiment held off massed wave attacks by Chinese communist troops in the most desperate action fought by the British Army since the Second World War. The men held on for three days until the last bullet was fired: a third of the battalion were killed or wounded, the survivors spent the remaining years of the war in Chinese or North Korean prison camps.

Even six decades on from the horrific battles they fought in, some Korea veterans sleep with the lights on. And in the cosy living room of his house in Byfleet, which he shares with his wife of 59 years, Jeanne, Moulder still chokes up when he recalls what he experienced - especially the death of his friend, Taffy.

He is proud of his service to his country - a Union flag still flutters from a pole in his front garden – but remains haunted by it, too. “The big thing is that the veterans talk to each other,” he says. “We don’t necessarily talk about the worse parts of it, but we talk about it all the same.”

Time, though, has taken its toll in other ways. Only last month, Major General Sir Peter Downward, the BKVA’s former president and patron, was the latest to appear in a newspaper obituary. Following Wednesday's event, the association will hang up its national standard for good at York Minster on January 18, and officially disband - although local branches will continue.

Yet now, on the banks of the River Thames, a Korea soldier stands who will not age. The memory - however painful – of Britain’s forgotten war, is finally set in stone.